Don’t you hate it when you miss something glaringly obvious? I’ve never seen the Triceratops skeleton at London’s Natural History Museum in person, but I’ve seen enough pictures to know that it’s a little weird. Inaccuracies like the columnar feet, dragging tail, and vertical forelimbs can be attributed the display’s age, but the head doesn’t really look like any other Triceratops skull that’s ever been found. I had assumed that the funky frill and extremely long nasal horn were sculpted flourishes, but it turns out that no part of this Triceratops is real. It’s not a heavily-reconstructed original skeleton or even a cast – it’s a papier mâché model. And not just any model, but one that I’ve already written about in a different context.

The Lucas Triceratops model at the 1901 Pan-American Exhibition. Source

Frederic Lucas, an Assistant Curator at the United States National Museum, created this Triceratops in 1900for the Smithsonian display at the Pan-American Exhibition in Buffalo, New York. A mix of corporate and government displays based around the themes of peace, prosperity, and technology, the Pan-American Exhibition lasted from May to November 1901 (it was cut short when President William McKinley was shot on the fairgrounds). The Smithsonian’s 7,500 square foot exhibit took nearly a year to prepare, and showcased specimens from all departments of the nascent institution. Indeed, the Smithsonian’s participation in this and other fairs around the turn of the century is significant because these attractions were the basis for the some of the first exhibits at the USNM. Displays initially created for fairs often found a home in the museum’s permanent galleries, and the fair exhibitions were generally used as a template for the first generation of Smithsonian exhibits.

The Triceratops model was meant to represent the glut of fossils from the western United States that the Smithsonian had recently acquired from O.C. Marsh. Perhaps because most of those specimens were still unpacked and unprepared (the USNM didn’t hire a dedicated fossil preparator until 1903), Lucas sculpted the skeleton freehand based on one of Marsh’s published illustrations. It’s noteworthy that Lucas was not a paleontologist – he was brought on board at the age of 21 with no formal training because of his talent for constructing taxidermy displays. At any rate, Lucas followed Marsh’s reconstruction – at the time the only Triceratops reconstruction available – religiously when constructing his full-sized model.

The Lucas Triceratops at the Louisiana Purchase Exposition in 1904. Source

After the Pan-American Exhibition, Lucas’s Triceratops made a second appearance at the 1904 Louisiana Purchase Exposition in St. Louis, Missouri. It was rendered obsolete shortly thereafter when Charles Gilmore assembled the world’s first real Triceratops skeleton at the USNM. As I’ve covered before, the act of physically manipulating the Triceratops fossils into a standing mount showed Gilmore that Marsh’s straight-legged reconstruction was a physical impossibility.

My understanding was that the Lucas model was lost or destroyed shortly after Gilmore’s real Triceratops went on display in 1905. I should have been more skeptical, however, because exhibits like this are almost never wasted. For example, Gilmore reported in 1943 that the Hadrosaurus cast displayed at the USNM before his arrival had been discarded due to wear and tear, but the mount had actually been given to the Field Museum in the 1890s. A couple months ago, I found out that Albert Koch’s chimeric mastodon (what he called “Missourium”) was purchased by Richard Owen on behalf of the British Museum and remounted. And just this year, the Smithsonian’s 112 year-old Stegosaurus model began a new life at the Museum of the Earth in Ithaca, New York.

The above tweet from the London Natural History Museum finally clued me in that the Lucas Triceratops had been hiding in plain sight for more than a century. The NHM (then the British Museum) received their Triceratops from the Smithsonian in 1907 (confirmed in the July 1907 issue of The Museums Journal), just when the Smithsonian had an extra Triceratops on hand. The London model is plainly not a cast of Gilmore’s 1905 mount, but it does resemble the Lucas model in most every detail, from the way the legs are posed to the exaggerated horns and frill. The only clear difference I can see is in the position of the head, which is much more elevated in the photos from the Buffalo and St. Louis expositions. However, I imagine the model would have been partially disassembled for transport. Perhaps when it was rebuilt in London the head ended up lower, whether by accident or design.

Unless there’s reason to think there were two copies of the Lucas Triceratops, I’d say the most parsimonious conclusion is that the London Triceratops is the very same model that was first displayed at the Pan-American Exhibition in 1901. Much like it’s long-time companion Dippy the Diplodocus, this Triceratops model is a century-old historic icon, one that has introduced generations upon generations of visitors to the enormity of deep time and the wonders of our prehistoric past. Inaccurate sculpture or not, it’s definitely something to preserve and to celebrate.

UPDATE: Shortly after I finished this post, @NHM_London responded to my inquiry with the following:

I’m dubious that the NHM Triceratops is a copy of Gilmore’s 1905 version, but hey, it *is* their museum. I’ll leave this post up for now and follow up when I find out more. I love a good museum mystery!

References

Gilmore C.W. (1905).The Mounted Skeleton of Triceratops prorsus. Proceedings of the U.S. National Museum 29:1426:433-435.

Gilmore, C.W. (1941). A History of the Division of Vertebrate Paleontology in the United States National Museum. Proceedings of the United States National Museum 90.

Over the past few months, I’ve been writing about the strengths and weaknesses of various large-scale paleontology exhibits from an educational standpoint. Check out the Introduction, Walk Through Time, Phylogeny, and Habitat Immersion posts if you’d like to catch up. I’ll wrap up this series for the time being with a look at two upcoming renovations of classic fossil displays, which appear to have converged on similar aesthetic, organizational, and interpretive approaches.

First up is the Peabody Museum of Natural History, where the Great Hall of Dinosaurs and adjacent Hall of Mammal Evolution have seen little modification since the 1950s. While the PMNH fossil galleries are fascinating as a time capsule of mid-century exhibit design, much of the content is rather dated and a thorough overhaul is sorely needed. PMNH staff started planning for the renovation in 2010, and I highly recommend Collections Manager Chris Norris’sblog postson the process. Once the basic layout and concepts were in order, the museum hired the architectural firm Studio Joseph to prepare the images being used to promote the project. Fundraising is now underway, but an estimated completion date has yet to be announced.

Conceptual render of the Great Hall of Dinosaurs by Studio Joseph. Source

The big idea behind the new exhibit is the dynamic relationship between the biosphere and the Earth’s various other spheres (atmosphere, geosphere, hydrosphere, etc). The evolution of life on Earth did not occur in a vacuum, but as part of a continuously changing global system. This narrative does have a time axis – visitors will travel from the Permian at one end of the exhibit to the Quaternary at the other – but the precise divisions of geologic time are de-emphasized in favor of the broad environmental transitions that triggered evolutionary innovations. Examples might include the separation of continents during the Mesozoic, the diversification of flowering plants in the Cretaceous, or the massive climatic shift at the end of the Eocene. In this context, it’s more important that visitors understand (for example) that the Cenozoic was generally a transition from hot and wet to cold and dry (and the implications on mammalian evolution) than that they know the names and time spans of each epoch.

This approach contrasts sharply with traditional chronological exhibits, such as the Field Museum of Natural History’s “Evolving Planet.” The FMNH fossil galleries are extremely linear, and each geologic period is introduced with a set of easily-digested bullet points summarizing what happened during that time. Relatively tight spaces prevent visitors from seeing specimens from other time periods prematurely, and the galleries devoted to each period are color-coded to make them immediately distinct. According to Norris, this segmented presentation of the history of life obscures the large-scale transitions which transcend the somewhat arbitrary divisions of geologic time. As such, the new PMNH fossil halls will present the narrative holistically, encouraging visitors to track the underlying environmental trends that precipitated evolutionary change over time.

As is immediately clear from the promotional images, the new exhibit will juxtapose a modern, wide-open aesthetic with elements of the museum’s past – specifically, the outdated but gorgeous Rudolph Zallinger murals. Both of these design elements tie directly to exhibit’s narrative themes. By breaking up the central dinosaur pedestal and eliminating the unsightly glass cases in the Mammal Hall, the exhibit designers have dramatically increased the available floor space and opened up new lines of sight. This should allow visitors to view each of the galleries comprehensively, rather than as a series of discreet segments. Meanwhile, the Zallinger murals will remain a celebrated part of the exhibits. These magnificent frescoes were painted between 1942 and 1967, and are among the most iconic images of prehistoric life ever created. Although the physiology of some of the animals is outdated, Zallinger was in other ways ahead of his time. Rather than giving the geologic periods hard borders, Zallinger artfully wove the sections together so that each one fades imperceptibly into the next. The viewer can see that the flora, fauna, and climate are changing over time, but it’s a gradient, not a ladder, which perfectly reflects the narrative of the new exhibit.

A conceptual render of Deinonychus and other Cretaceous fossils. Source

About 300 miles south of PMNH, the re-imagining of the fossil halls at the National Museum of Natural History is well underway. This building’s east wing has been home to paleontology displays since it opened in 1910 and has been updated several times, but this is the first time it has undergone a complete, wall-to-wall modernization. The old exhibits were formally closed on April 28th, 2014, and NMNH staff spent the following year removing thousands of specimens from the halls. With the fossils out of the way, the next step will be to restore the historic space to its original neoclassical glory. After that, the new exhibits and updated fossil mounts can be assembled in time for a 2019 re-opening.

Intriguingly, the planned design of the new National Fossil Hall is both thematically and aesthetically similar to the PMNH renovation, albeit on a grander scale. The National Fossil Hall’s narrative focus will be on large-scale environmental transitions over time, and how these changes drove the evolution of plants and animals. Like at PMNH, this will be accentuated by an open layout: false walls and barriers that have divided the space since the early 1960s will come down, allowing visitors to see clear across the spacious three-story hall. This airy aesthetic hearkens back to the Hall of Extinct Monsters, and like the restoration of the Zallinger murals at PMNH it represents an admirable celebration of the institution’s history.

Early conceptual render of the National Fossil Hall by Reich + Petch Source

One interpretive choice that will set the National Fossil Hall apart is the clustering of specimens on islands, or “pork chops”, as the were called early in development. Each pork chop represents North America at a particular period in time. While anchored by a few charismatic mounts, the pork chops will also include all manner of small animals, invertebrates, and plants that were part of that environment. In this way, the islands are self-contained mini exhibits, each one showing a complete ecosystem that existed at a particular time. Moving among the these displays, visitors should get a sense of how climate change and faunal interchange (among other phenomena) can completely transform an ecosystem over millions of years. They’ll also learn how certain organisms, like sauropods in the Jurassic or grass in the Neogene, can change landscapes and influence the evolution of contemporary plants and animals.

The emphasis on open spaces and freedom of movement is notable, because this is quite different from the linear exhibits of the late 20th century. In recent decades, exhibits have become increasingly structured, with specific learning goals and physical spaces designed to corral visitors through a carefully orchestrated narrative journey. Again, Evolving Planet at FMNH is an excellent example of this philosophy. The new National Fossil Hall is in some ways a push in the opposite direction – although it has a clear narrative and overarching message, visitors can roam through the exhibit as they please. I see the pork chop system as a way to have it both ways. Whether visitors work through the exhibit front to back or run straight to the T. rex in the center of the hall, then wander around at random, they’ll still be able to compare and contrast the different ecosystems and learn what the designers want them to learn.

Early concept art of the Jurassic “pork chop.” Image from The Last American Dinosaurs, NMNH.

More than anything else, what I expect to set the National Fossil Hall apart from peer exhibits will be its explicit connections to modern-day environmental crises. It’s worth quoting the Department of Paleobiology’s summary in full:

Visitors to the Museum will be able to explore how life, environments, and ecosystems have interacted to form and change our planet over billions of years. By discovering and harnessing the tools and methods paleobiologists use to study fossils, visitors will gain a deeper understanding of how the world works.

The distant past affects all of us today and will continue to do so in the future. How will climate change impact the natural world and our daily lives? How can we make informed choices about our ecosystems as individuals and as a species? How can we all become informed citizens of a changing planet?

We are in the midst of an extinction event of our own making. Anthropogenic climate change, habitat destruction, and invasive species are as dangerous as any asteroid, and will likely have profound effects on our own lives and livelihoods in the coming century. But while humans are undeniably the cause of the latest round of global changes, we also have the power to mitigate and manage their consequences. The study of fossils provides important contextual information – we can place modern organisms in an evolutionary context and understand their role in shaping the world as we know it, and we can see how organisms have responded to significant environmental overhauls in the distant past. The fossil record is in fact the only way to directly observe these things (as opposed to relying on models or actualistic experiments). As such, the new National Fossil Hall will make it clear that paleontology isn’t just about historical curiosity. The study of past life gives us a long view of the Earth’s biotic and abiotic systems, and helps us predict how they will respond to today’s environmental changes.

Concept drawing of the National Fossil Hall’s Cretaceous zone. In the old hall, the viewer would be standing at the base of the mezzanine stairs facing the rotunda. Source

With the modern climate crisis front and center, the new National Fossil Hall has the potential to be one of the most immediately relevant and important paleontology exhibits ever assembled*. This is significant, because as I lamented when I started this series, immediacy and relevance are not things that most museum visitors expect from fossil displays. While fossils, particularly the mounted skeletons of dinosaurs and other prehistoric animals, have been central to the identity of natural history museums since the late 19th century, most visitors don’t regard these exhibits as anything more than prehistoric pageantry. Visitor surveys consistently reveal that dinosaurs are seen as eye candy – monsters that might as well be from another planet. This is a shame, because dinosaurs and other prehistoric organisms were real parts of our own world, and we can learn much from them.

The new National Fossil Hall will be arranged in reverse chronological order – as visitors move accross the gallery, familiar elements of modern environments will be stripped away and the world will become an increasingly alien place. Source

And so we come full circle. What is the point of a museum exhibit**? Is it enough to provide visitors an opportunity to see cool objects and specimens? When we ask museumgoers what they want to see, they tell us “dinosaurs” or “fossils.” They don’t ask for compelling narratives or connections to big contemporary issues, and they don’t see their museum visit as an important way to bridge gaps in scientific literacy.

Still, it is of critical importance that we provide these narratives and connections. Even if we accept the fact that the very existence of a museum and the chance to see real specimens is a Good Thing, museums are still accountable to the public. Virtually all museums cite education as the primary purpose of their institution, and it’s imperative to live up to that. A museum should have a learning goal in mind, it should be able to prove that this message is coming across, and it should be able to articulate why its audience is better off for it. This is not necessarily easy – exhibits need to be relevant without being condescending or preachy. Exhibit designers need to understand their visitors as much as their content. They need to find a balance between feeding visitors information and providing a customizable experience for diverse audiences. As we have seen, not every exhibit succeeds, but my impression is that we’re getting better at it.

*It’s also notable that this climate change-focused exhibit will be on the national mall, given the ongoing politically-motivated opposition to climate science.

**Note that I’m referring specifically to public-facing exhibits. There are many good reasons why the ongoing maintenance of natural history collections is intrinsically valuable.

References

Marsh, D.E. (2014). From Extinct Monsters to Deep Time: An ethnography of fossil exhibits production at the Smithsonian’s National Museum of Natural History. http://circle.ubc.ca/handle/2429/50177

Today’s topic is immersive exhibits – walk-through artificial environments that realistically simulate the prehistoric world. There are plenty of examples, and notably most have been built in the last 30 years. The Cincinnati Museum Center has a reconstruction of the Ohio Valley during the Pleistocene. The centerpiece at the Sternberg Museum of Natural History is an indoor forest presided over by an animatronic Tyrannosaurus rex. Probably the most dramatic example is the DinoSphere at the Children’s Museum of Indianapolis. Here, a repurposed Imax theater contains a number of dynamically posed dinosaur skeletons standing among rocks and trees. The surround sound system provides a constant soundtrack of animal calls, while the projection screen shows the sky at different times of day on a 22-minute cycle. There are even periodic storms, complete with flashing lights and booming thunder.

Stan and Bucky harass a Triceratops in the DinoSphere.

Exhibits like the DinoSphere and its kin are frequently derided as sensationalism with little educational value. These multi-million dollar special effects shows (which sometimes do not contain any genuine specimens at all) are plainly inspired by the successes of theme parks, and it’s easy to dismiss them as crass efforts to draw crowds with flashy gimmicks. Surely these exhibits are nothing more than misguided attempts to turn museums into entertainment, learning opportunities be damned?

Well, it depends. The role of spectacle in museums is a complex one, and arguably one that is impossible to decouple from the core identity of these institutions. Going back to the enlightenment-era cabinets of curiosities from which modern natural history museums emerged, the public side of museums has always been about showing off the biggest, the rarest, or the most expensive. And this sensationalist modus operandi has often been reflected in the spaces where specimens are displayed. The Greco-Roman architecture of classic exhibit halls, for example, is no less artificial than the DinoSphere’s indoor thunderstorms, and serves pretty much the same purpose.

The neoclassical aesthetic of the Field Museum’s great was designed to impress – and is no less of a fabricated experience then the DinoSphere above. Photo by the author.

While spectacle in museums is nothing new, neither is its complicated relationship with education. Arresting displays have long been leveraged to imbue specimens with informative context. Take habitat dioramas populated by taxidermy animals, a longstanding staple of natural history museums. These little worlds behind glass first became popular in the mid 19th century, and were almost immediately controversial among museum workers. Paradoxically, dioramas provided visitors with a fuller appreciation of the ecosystems the animals lived in, but only by wrapping the specimens in a layer of theatrical artifice. The immersive fossil exhibits that have cropped up over the last few decades are essentially habitat dioramas on a larger scale, and exhibit designers are still wresting with the same issues their forebears did a century and a half ago. Which is more important in the context of public exhibits – an informative and meaningful narrative, or authenticity?

For me, spectacle and artifice are fine, even welcome, so long as they serve a purpose. In some cases, the spectacle exists to inform (as in a habitat diorama), in other cases the spectacle itself is the attraction. The robotic T. rex at the Natural History Museum in London and the neanderthal photo booth at the National Museum of Natural History come to mind as examples of the latter – they’re entertaining, but don’t facilitate any further reflection or inquiry. When implemented in a thoughtful and deliberate way, however, spectacle can be a powerful element in a museum educator’s toolkit.

By design, the first big skeleton visitors see in Dinosaurs in Their Time isn’t a dinosaur – it’s the phytosaur Redondasaurus. Photo by the author.

Let’s look at one example of a habitat immersion exhibit that uses showy reconstructed environments to maximize its educational potential. Two years and $36 million in the making, “Dinosaurs in Their Time” at the Carnegie Museum of Natural History is, in my opinion, one of the absolute best paleontology exhibits in the world*. Whether you’re considering the scope and quality of the specimens on display, the aesthetics and layout, or the interpretive approach, Dinosaurs in Their Time is a benchmark in natural history exhibit design. You can follow along with this nifty interactive map.

*To be absolutely fair, Dinosaurs in Their Time is focused exclusively on the Mesozoic, which makes it difficult to compare to larger exhibits that cover the entire history of life on Earth.

What makes Dinosaurs in Their Time so great? Let’s start by considering the layout. The new exhibit more than doubles the square footage of the old Carnegie dinosaur hall, and much of the interior is actually a former courtyard (incidentally, this reuse of an existing space helped the exhibit earn its LEED certification). This makes the gallery spacious and airy, with a high ceiling and plenty of natural lighting. The exhibit is arranged chronologically, starting in the Triassic and ending in the Cretaceous, but there is plenty of space in which to roam. In fact, the pathway forms a sort of figure eight around the Apatosaurusand Diplodocusin the Jurassic zone and the Tyrannosaurus pair in the Cretaceous. This cyclical organization allows, if not encourages, visitors to view specimens from multiple perspectives, and lets each person traverse the exhibit at their own pace. It’s especially nice that the sauropods have enough room to breathe – too often, these immense skeletons are relegated to cramped quarters where it’s impossible to see them all at once.

Visitors can walk all the way around Apatosaurus and Diplodocus, and even view them from above. Photo by the author.

The open spaces and clear sight lines are nicely complemented by the reconstructed rocks and foliage that fill the exhibit, giving it a proper outdoor feel. Importantly, the flora isn’t just for show – it’s a critical component of the interpretation. “We’ve painstaking recreated the worlds of the dinosaurs,” curator Matt Lamanna explains in a Carnegie Magazine interview, “everything that is displayed together actually lived together.” One of the key themes in Dinosaurs in Their Time is that dinosaurs were but one part of rich ecosystems, which were just as complex as those of today. These animals shaped and were shaped by the world around them, and there is far more to paleontology than the pageant show of toothy monsters that many visitors have come to expect. Indeed, it’s more akin to reconstructing entire worlds.

The plurality of “worlds” is important, because Dinosaurs in Their Time also emphasizes the nigh-unfathomable time span of the Mesozoic. Over 185 million years, countless communities of organisms came and went, and once again the immersive aesthetic of the exhibit helps convey this. While the horsetail swamp of the Triassic area almost looks like an alien world, the Cretaceous is populated by flowers and deciduous trees much like those of today. In this exhibit, the fossil specimens aren’t in a neutral environment – the space itself is part of the narrative.

Tyrannosaurus and Triceratops mounts stand among flowers and magnolias. Photo by the author.

The habitat immersion approach comes with yet another plus: it encourages exploration. From a tiny swimming Hyphalosaurus under the waterline of an artificial pond to a Rhamphorhynchus halfway up a tree, visitors are constantly rewarded for looking high and low. As Lamanna explains, “many visitors are repeat visitors, so we wanted to give them something new to discover every time they come back.” This is particularly beneficial for younger visitors. Rather than barreling through the exhibit in minutes, kids are encouraged to look for tiny details and learn things along the way.

Finally, the computer terminals throughout Dinosaurs in Their Time merit some discussion because they embody the same multi-tiered educational approach as the physical space around them. Dinosaurs in Their Time actually tells several stories simultaneously: there’s the ecology story, the deep time story, the history of the specimens on display, and even a meta-story of how the new exhibit was put together. Most visitors won’t be interested in every narrative, nor should they be. Rather than filling the walls with a dizzying array of signage, the exhibit designers consolidated the various narratives into space-efficient interactives. Visitors can choose which information they would like to see, and craft their experience in the exhibit to their tastes. This is technology used intelligently and purposefully, and something I hope to see other exhibits emulate in the future.

Sharp-eyed visitors are rewarded with hidden specimens, like this Rhamphorhynchus halfway up a tree. Photo by the author.

The purpose of any exhibit structure is to provide meaning and context for objects – to help visitors see them as more than neat things to look at. It’s the museum’s job to give visitors the intellectual tools to contextualize displayed objects in a more sophisticated way. Spectacle is one way to achieve that goal, and Dinosaurs in Their Time is a stellar example.

The frentic search for North American dinosaur fossils in the late 19th and early 20th centuries can be divided into three phases. First came O.C. Marsh and E.D Cope, whose infamous rivalry resulted in literal trainloads of fossil material and laid the groundwork for our present understanding of dinosaur diversity. Next, teams sponsored by the newly-formed American, Carnegie, and Field museums returned to the same hunting grounds in the western interior to secure display-worthy specimens for their great halls of exhibition. The final phase was smaller in scale but yielded dinosaur specimens so spectacularly complete that most have gone unmatched to this day.

This third fossil rush occurred not in the United States but in Canada, along the cliff-like banks of Alberta’s Red Deer River. Fossil hunting in this region was pioneered in the late 1800s by George Dawson, Joseph Tyrell, and Lawrence Lambe, all working for the Canadian Geological Survey. This success did not go unnoticed by the the American Museum of Natural History’s Department of Vertebrate Paleontology. In 1910, the museum mounted an expedition led by Barnum Brown to the Red Deer River. Rather ingeniously, Brown’s team acquired a pair of 30-foot floating barges, which were used as mobile platforms from which they could excavate the steep river banks. The barges also served as floating campsites and a handy means of transportation in a region without reliable roads.The adventurous Brown was already a media favorite, and the publicity surrounding his Alberta expeditions only increased when the team started bringing back fully articulated and nearly complete dinosaur skeletons (including several with skin impressions).

Under pressure from constituents concerned that the Americans were hauling away so much of their natural heritage, the Canadian government formed its own team of fossil collectors in 1912. The new Canadian Geological Survey team was headed by independent fossil hunter Charles H. Sternberg (a veteran collector who had once worked for Cope) and his sons George, Levi, and Charles Jr. The Canadian and American teams worked in the same region for the next five field seasons. Their rivalry was usually good-natured, but on more than one occasion Brown saw fit to grumble about the Sternbergs’ ethics (never mind that he was the one permanently removing fossils from their country of origin).

All of this is so much preamble for the actual topic of this post – three remarkable Gorgosaurus skeletons* collected near the Red Deer River during the Canadian fossil rush. All three were eventually mounted in relief by AMNH preparator Peter Kaisen, and for a time they were displayed together in the Hall of Fossil Reptiles. These specimens are on the short list of most complete large theropod dinosaurs ever discovered, and in their day they provided researchers an unprecedented look at the physiology of these amazing animals. Nearly a century later, the three mounts are virtually unchanged. Locked behind glass for decades and largely inaccessible to researchers, the mounts themselves are now relics of a fascinating transitional period in the history of dinosaur studies.

As usual, a brief explanation of nomenclature is required. William Matthew and Barnum Brown originally described these specimens as Gorgosaurus, a genus that Dale Russell sank into Albertosaurus in 1970. Most specialists no longer support this synonymization, but the specimens at AMNH are still labeled as Albertosaurus.

Gorgosaurus libratus – USNM 12814

A recent photo of USNM 12812 from the ongoing renovation of the national fossil hall. Source

USNM 12814 (originally designated AMNH 5248) was excavated by Brown’s company in 1913 and prepared for display in 1918. Kaisen elected to recreate the death pose in which the Gorgosaurus was found, with its head swept backward over its body. All told, the finished mount included a skull, a complete set of cervical and dorsal vertebrae, complete forelimbs, and a single femur – the pelvis and the rest of the hindlimbs were filled in with casts from other specimens. Since the skeletonwas mounted in relief, Kaisen simply painted the tail onto the backdrop.

After at least a dozen years on display at AMNH, the Gorgosaurus was traded to the National Museum of Natural History as part of a complicated deal between the two museums. While surveying fossil collections throughout the United States, Brown realized that a single Barosaurus skeleton from Dinosaur National Monument had been divided among three different institutions. NMNH had the neck and part of one forelimb, the Carnegie Museum had the tail, and the University of Utah had the rest. Between 1929 and 1933, Brown arranged a series of trades in order to unify the Barosaurus at AMNH. The Smithsonian in particular drove a hard bargain – the museum had already invested $3400 in preparing their Barosaurus section, and paleontology staff wanted a good return for their investment. Brown’s initial offer was the fully prepared and mounted Gorgosaurus. Although AMNH valued the field and prep time spent on the fossils at $4573, it was at that point a duplicate specimen taking up valuable space in their increasingly crowded exhibit hall.

NMNH dinosaur specialist Charles Gilmore confided in Brown that he was okay with this trade, but fellow Smithsonian paleontologist Alexander Wetmore wasn’t sold. For years, NMNH staff had been trying to acquire one of the many Moropus specimens AMNH had collected at the Agate Fossil Beds in Nebraska.NMNH had offered a variety of specimens to trade, even sending AMNH a set of brontothere skulls at one point, but AMNH was adamant the Moropus fossils could only be exchanged for cash. Brown really wanted that Barosaurus neck, so in January of 1933, he finally relented and offered the Smithsonian a largely complete Moropus in addition to the Gorgosaurus. Not long after, the Gorgosaurus relief mount found its way into the Hall of Extinct Monsters at NMNH.

Gorgosaurus sp. – AMNH 5458

Brown’s team found their second Gorgosaurus near Steveville, Alberta in 1914. Complete save for the left leg, right arm, and parts of the rib cage and tail, the mount was ready for display in May of 1921. At 24 feet long and 14 feet high, this was by far the largest relief mount at the museum. In fact, it was too big to fit through the workshop doorway in one piece, so Kaisen constructed it in eight sections that were sealed together in the exhibit hall. Each section had its own wooden frame for support, and the bones themselves were held in place with steel straps. The skull, jaw, and left forearm could be removed for individual study. This was unusual for the period (most contemporary fossil mounts were designed to be permanent) and speaks volumes about this specimen’s unique scientific value.

This mount is particularly notable for its awkward running pose. Directly contradicting many narratives of early 20th century paleontology, Matthew and Brown envisioned Gorgosaurus as an animal that “walked and ran much like a gigantic bird.” The AMNH team posed this mount after studying photos of bipedally running lizards, particularly the western tiger lizard*. However, Matthew and Brown noted that the dinosaur’s limb proportions and range of motion more closely resemble a bird than a lizard, and adjusted the pose accordingly. They also advised a more conservative stride length to compensate for the animal’s considerable weight.

*Matthew and Brown do not provide a scientific name, and the common name “western tiger lizard” doesn’t seem to be used any more. Anyone know what it’s called today?

The final pose was a compromise between the elevated torso of a running lizard and the comparatively tight gait of a bird. It looks more than a little strange, but AMNH 5458 is certainly closer to our present understanding of theropod posture than most mounts of the era. Matthew and Brown’s interpretation of Gorgosaurus turned out to be ahead of its time. Some contemporary researchers, including Lawrence Lambe, declared the running pose to be highly improbable, and virtually all theropod mounts constructed over the next 60 years returned to the tail-dragging posture of the 1915 AMNH Tyrannosaurus.

Gorgosaurus “sternbergi” – AMNH 5664

Gorgosaurus “sternbergi” as it was discovered and originally mounted. Source

The most complete tyrannosaur from the Red Deer River was not collected by the AMNH party, but by the Sternbergs. The elder Charles Sternberg discovered the specimen in 1917, entirely intact save for the left arm and the very end of the tail. In fact, this was the most complete large theropod ever found in North America until it was surpassed by yet another Gorgosaurus, TCM 2001.89.1. Sternberg first attempted to sell the specimen to the British Museum. They weren’t interested, but AMNH was. In 1918, the Department of Vertebrate Paleontology bought the skeleton for $2000, thus completing the tyrannosaur trio.

Matthew and Brown described AMNH 5664 as a new species – Gorgosaurus sternbergi. In their 1921 publication, they describe the skull as longer and shallower than other Gorgosaurus specimens, with rounder orbits. However, Brown and Matthew recognized that these could be juvenile characteristics, noting as well that the unfused pelvic bones were an indication of immaturity. As early as 1970, this specimen was suspected to be a juvenile Gorgosaurus (or Albertosaurus) libratus.

Kaisen prepared the relief mount in 1921, this time assisted by Carl Sorenson. The photo above shows the original version of this mount, with the tail projecting straight back from the body. This was how Sternberg discovered the skeleton, and Kaisen wanted to keep the death pose intact. In the 1950s, the tail was “corrected” to make it drag on the ground. Although the display has not been altered since, the revised tail posture is now considered inaccurate. Indeed, the vertebrae apparently had to be angled unnaturally to make the dragging tail work at all.

All three Gorgosaurus specimens were first displayed in the cramped quarters of the Hall of Fossil Reptiles (now the Hall of Primitive Mammals) with the rest of the growing AMNH dinosaur collection (USNM 12814 and the tail of AMNH 5664 are barely visible in this photo). 5458 and 5664 moved to the newly opened Great Hall of Dinosaurs in 1922. They flanked the gallery’s rear doorway for 70 years before being moved to the Hall of Saurischian Dinosaurs in 1994. Meanwhile, the Gorgosaurus transferred to the Smithsonian first appeared in the Hall of Extinct Monsters in the 1940s, displayed behind glass on the north wall. It switched to the south side in 1962, and moved about 30 feet up the wall in 1981, where it could only be properly seen from the mezzanine ramp.

Aside from the aforementioned alternation to AMNH 5664’s tail, the Red Deer River Gorgosaurus trio has not been modified since they were first built. This may well change in the not-to-distant future. The NMNH crew is hard at work on a thorough renovation of the national fossil hall, dismantling and restoring all of the classic dinosaur mounts. Meanwhile, the current AMNH paleontology exhibits are now 20 years old, and will soon be due for a similar overhaul. Both institutions will need to decide whether or not to free the Gorgosaurus specimens from their plaster substrate. This would be an extremely difficult process, but not impossible – Phil Fraley Productions recently rebuilt the Carnegie Museum’s Corythosaurus, Dryosaurus, and Camptosaurus as free-standing mounts. Dismantling the relief mounts would give a new generation of scientists access to these important specimens, and it would allow for the skeletons to be given more accurate poses. In addition, a standing Gorgosaurus mount alongside either museum’s Tyrannosaurus rex would be both informative and awesome.

Nevertheless, remaking these mounts would also destroy significant historical context. The carefully restored death pose of USNM 12812 seems like something worth preserving, and the AMNH specimens represent an important transitional period in the history of dinosaur science. In the past, museums have often taken a “science marches on” approach when updating aging displays, but in these mounts might be unique enough in their current form to be left as-is. What do you think?

I was planning to be bitter and jaded about “Jurassic World”, but my excitement has gotten the better of me. I like much of what I’ve seen so far, and I’m looking forward to seeing the film next week. Moreover, the cultural endurance of the original “Jurassic Park”, now 22 years old, is incredible. When leading tours, I am regularly asked about the (largely fanciful) ground-penetrating radar shown in the movie. The word “dromaeosaur” results in blank faces, but if I call it a “raptor-type dinosaur, like in Jurassic Park,” I get knowing nods. These movies are the frame of reference for the public’s understanding of paleontology – not just how dinosaurs looked and behaved, but how scientists learn about them.

An important digression: we can’t give sole credit for Jurassic Park’s outsized role in popular culture to its dinosaurs and visual effects. I doubt the film would have the same lasting power without its memorable story and characters. Jurassic Park turned the classic lost world fantasy on its head, mixing it with a modern, tech-infused setting and a believable – albeit impossible – method for bringing dinosaurs back to life. The film raises concerns about the corporate commodification of GMOs that (whether reasonable or not) are at least as relevant today as they were in 1993. The entertaining and relatable way in which Jurassic Park broaches complex topics has not gone unnoticed by teachers. More than two decades later, the film is still being used to introduce subjects ranging from bioethics to complex mathematics.

Meanwhile, Jurassic Park features some of the most true-to-life scientist characters I’ve ever seen in a popular film (a very low bar, to be fair). Alan Grant has a quiet, thoughtful demeanor that reminds me of a number of colleagues and acquaintances. He usually thinks before he speaks or acts, but he also has a playful side that demonstrates the absolute joy he takes in discovering things about the world around him. Ian Malcolm, on the other hand, is what is known as an academic asshole. Like certain celebrity scientists, he’s a self-righteous jerk who may have some wisdom to impart, but chooses to do so in an insufferably arrogant and aggressive way. Scientists are as complex as anyone else, and it’s nice to be able to point to a movie that goes beyond the usual nerds in lab coats. Some more diversity among the principal cast would be better, but Jurassic Park is a move in the right direction.

A very reasonable reaction upon encountering a living Triceratops. Source

Back to my main point, the Jurassic Park films have had a meaningful and substantial impact on popular impressions of dinosaur science, and in this respect they should be taken seriously. A substantial amount of ink and pixels has been spilled regarding the accuracy (or lack thereof) of Jurassic Park’s dinosaurs for precisely this reason. Since the first Jurassic World trailer was released last fall, much of this conversation has revolved around the retrograde appearance of the new film’s saurian stars – rather than taking advantage of two decades of new science, the filmmakers stuck with the early 1990s designs. Experts have called this choice “lazy,”“a missed opportunity,” and “unbearably stupid in every conceivable way.” In response, die-hard Jurassic Park fans are rushing to the film’s defense. Many have explained away any deviations from real dinosaurs by pointing out that the cloned animals are genetic aberrations to some degree. Maddeningly, others have taken to questioning what experts truly know about extinct animals.

Misguided appeals to ignorance can be dismissed out of hand, but the “cloned aberrations” argument deserves attention, if only because it completely misses the point. The Jurassic Park series has always been viewed (and marketed) as credible science fiction. The filmmakers hired Jack Horner, probably the world’s best-known paleontologist, to vouch for the dinosaur designs of all four films. By the time the third movie came out, special effects genius Stan Winston (rest in peace) was claiming that they had “blurred the theatricality of movies with museum-type education,” and that “there’s something to be learned from watching these movies” (quotes from DVD featurette “The Dinosaurs of Jurassic Park III”). Given statements like these, it’s important that anyone with a vested interest in natural history education be aware of the films’ content, and be prepared to call out inaccuracies as necessary.

Nevertheless, I’d also like to direct some finger-wagging at those who seem excessively eager to tear down the Jurassic Park films in the name of education. Many otherwise reasonable adults care a great deal about these movies, and “classic” dinosaur depictions in general. Perhaps this is due to an association with childhood, or perhaps it’s a manifestation of “awesomebro” culture. Either way, my job and my passion is to communicate the amazing discoveries scientists are making about our world, but I also know that telling people the things they like are stupid and wrong isn’t a great way to win over hearts and minds. Rather than alienating and antagonizing potential learners, I’d prefer to make use of what the audience is bringing to the conversation. Jurassic Park is a wide-reaching frame of reference and a helpful starting point for conversations about what we know about past life and how we know it. As I’ve argued before, the ideal approach is to acknowledge the relevance of pop-cultural dinosaurs, while working to separate them in our audience’s minds from the real dinosaurs that we learn about by studying fossils.

As an educator, what I want out of Jurassic World is a good movie, full stop. A good movie is a memorable movie, one that inspires people to visit parks and museums and to read up on paleontology. In more substantive terms, the original Jurassic Park also brought forth a great deal of funding for new research and museum exhibits, simply by creating awareness that dinosaur science has popular appeal. So to director Colin Trevorrow and Jurassic World, I say bring it on. We’re ready for your inaccuracies, and we’re ready to turn them into great discussions.

Some time ago, I wrote about the O.C. Marsh dinosaurs at the National Museum of Natural History. These are the mounted skeletons made from the enormous collection of fossils Marsh accumulated while working for the United States Geological Survey – if you’d like, you can catch up with Part 1 (on Edmontosaurus and Triceratops) and Part 2 (on Camptosaurus, Ceratosaurus, and Stegosaurus). Looking back, I noticed that I never actually finished, so here are the two Marsh dinosaurs with as-yet untold stories.

The Thescelosaurus

The name Thescelosaurus neglectus means “neglected wonderful lizard”, because Smithsonian paleontologist Charles Gilmore found the original specimen at the bottom of a crate, more than 10 years after it arrived at NMNH. Still buried its its field jacket, this skeleton had been long overlooked by both Marsh and the museum staff. Nevertheless, Gilmore found that it was remarkably complete and that it represented a taxon new to science.

An illustration of the Thescelosaurus holotype prior to reconstruction. Source

The specimen that would become the Thescelosaurus holotype (USNM 7757) was excavated by John Bell Hatcher and William Utterback in July of 1891, while they were collecting for Marsh in Niobrara County, Wyoming. 20 years later, Gilmore discovered that the skeleton was articulated and intact, save for the head, neck, and parts of the shoulder. He even found small patches of preserved skin on the tail and legs. According to Gilmore, the animal had been buried rapidly after death, since it showed no signs of dismemberment by scavengers.

After describing the fossils, Gilmore had the Thescelosaurus mounted in relief on its left side. Other than the reconstructed skull (modeled after Hypsilophodon), the specimen was displayed almost exactly as it was found. This was important to Gilmore, because as he wrote in his published description, “I am…of the opinion that specimens so exhibited hold the attention of the average museum visitor far longer and arouse a keener interest in the genuineness of the specimen than does a skeleton that has been freed from the rock and mounted in an upright, lifelike posture.” Today at least, I suspect that the opposite is true – visitors are generally more impressed by dynamic standing mounts than by reliefs that preserve death poses. Still, it’s fascinating to gain a small amount of insight into the motivations of a pioneering mount-maker.

Thescelosaurus as displayed after 1981. Photo by Chip Clark.

Although it was first displayed in the Hall of Extinct Monsters, the Thescelosaurus was most prominently exhibited in the 1963 version of the NMNH fossil halls. Here, it joined the Edmontosaurus, Gorgosaurus, and partial Corythosaurus relief mounts along the south wall. In life, these animals were vastly removed from one another in time and space, but displayed together they almost appeared to be parts of a single quarry face. The Thescelosaurus moved to the north wall in 1981, unfortunately placed rather high and out of most visitors’ line of sight. Like the rest of the classic NMNH dinosaur mounts, this specimen is currently undergoing extensive restoration. Should it return in 2019, it will need a new head – in 2014, paleontologist Clint Boyd described the cranial anatomy of T. neglectus for the first time based on two recently discovered skulls.

The Allosaurus

Now that we have the boring ornithopod (oxymoron?) out of the way, let’s move on to the cool specimen! Built in 1981, the Allosaurus fragilis (USNM 4734) is the newest mount assembled from Marsh Collection fossils, although bits and pieces have been on display at NMNH since 1920. There has been considerable interest in this individual recently, in part because Kenneth Carpenter and Gregory Paul proposed in 2010 that it become the neotype for Allosaurus – more on that in a moment. Others are interested in this specimen because of its unique pathologies. In addition to several broken and healed bones, the Allosaurus has a massive puncture wound on its left scapula, which nicely matches the diameter of a Stegosaurus tail spike.

Benjamin Mudge collected this specimen in 1877 near Cañon City, Colorado. Known as the Garden Park quarry, this site also produced the Stegosaurus, Camptosaurus,and Ceratosaurus on display at NMNH. Although the Smithsonian obtained the Allosaurus with the rest of the Marsh Collection around 1900, Gilmore did not look at it (or any of the theropod material) until at least 1911. All told, USNM 4734 consists of a partial skull and jaw, a complete set of presacral and sacral vertebrae, part of the tail, a few ribs, a pelvis, and virtually complete arms and legs. Norman Boss assembled a reconstructed skull, which was displayed through the 1970s. The articulated legs and feet were exhibited in a free-standing case until the late 1950s.

This specimen’s taxonomic history merits some discussion. The holotype Marsh selected when naming Allosaurus (YPM 1930) is notoriously poor, consisting of a single phalanx, two dorsal centra, and a tooth. Dozens of very complete skeletons attributed to Allosaurus are now known, and most specialists basically agree on what an Allosaurus is, but the lack of a usable type with which to define the taxon has been an ongoing problem.

Mounted Allosaurus legs in the Hall of Extinct Monsters. Photo Courtesy of the Smithsonian Archives.

The far more complete USNM 4734 was recovered from the same quarry as the Allosaurus holotype, during the same 1877 field season. Marsh himself actually used this specimen, rather than his designated type, to illustrate subsequent publications on Allosaurus. In 1920, Gilmore flirted with the idea of nominating USNM 4734 as a neotype for Allosaurus, but for reasons that I find difficult to follow, he decided to lump both specimens into the older name Antrodemus valens. Joseph Leidy coined Antrodemus in 1870 based on a single caudal vertebra with no geologic provenance, so this move did little to fix the underlying issue. Nevertheless, Antrodemus remained a popular synonym for Allosaurus in some circles for several decades.

When the NMNH fossil halls were renovated in 1981, the designers presumably noticed that the exhibit badly needed a large theropod mount. Ken Carpenter was tapped to design and construct a complete mounted version of USNM 4734. The Allosaurus measures 17 feet from its grinning jaws to the tip of its tail, and a form-hugging armature makes itlook particularly dynamic. This mount has been a favorite among visitors for more than 30 years, although the 2001 addition of a Stan the Tyrannosaurus cast has somewhat overshadowed the smaller theropod.

The complete Allosaurus skeleton was finally exhibited in 1981. Photo by the author.

Technicians from Research Casting International took down the Allosaurus in the summer of 2014 as part of the current round of renovations. You can watch a video of the de-installation here. The skeleton will be remounted in a few years, but Smithsonian researchers want to get a good look at it before that happens. In particular, curator Matt Carrano has been wondering for some time whether a partial jaw Marsh named “Labrosaurus ferox” actually belongs to this specimen. The “Labrosaurus” jaw, which has an unusual pathology caused by a bite or twisting force, came from the same quarry as USNM 4734, and appears to be the same portion of jaw that the more complete skeleton is missing. Time will tell whether Carrano’s hunch is correct. Meanwhile, Carpenter and Paul’s petition to replace the Allosaurus type with this more complete specimen from the same locality is still pending. We should expect to hear more about that soon, as well.

References

Gilmore, C. M. (1915). Osteology of Thescelosaurus, an ornithopodus dinosaur from the Lance Formation of Wyoming. Proceedings of the U.S. National Museum 49:2127:591–616.

Gilmore, C.M. (1920). Osteology of the Carnivorous Dinosauria in the United States National Museum with Special Reference to the Genera Antrodemus (Allosaurus) and Ceratosaurus. United States National Museum Bulletin 110:1-154.

In the middle decades of the 20th century, museum theory and paleontological science were undergoing complementary revolutions. Museum workers shrugged off their “cabinet of curiosity” roots and embraced visitor-centric, education-oriented exhibits. Designers began to envision the routes visitors would travel through an exhibit space, and consider how objects on display could contribute to holistic stories. Meanwhile, paleontologists like Stephen J. Gould and David Raup moved their field away from purely descriptive natural history, exploring instead how the fossil record could inform our understanding of evolution and ecology. The common thread between both transitions was a focus on connections – bringing new meaning and relevance to disparate parts by placing them in a common narrative.

Between 1953 and 1963, the Smithsonian implemented an institution-wide modernization program, transforming virtually every exhibit in the museum complex. The National Museum of Natural History began renovations to its classic fossil halls in 1959, and the new exhibits were emblematic of contemporary trends in both museum design and paleontology. The plan, as devised by exhibit designer Ann Karras, was to do away with the loose arrangement of specimens and turn the east wing into a guided narrative of the biological and geological history of Earth. Responsibility for selecting specimens and writing label copy in each of the four halls fell to a different curator. In Hall 2, which housed dinosaurs and fossil reptiles, that curator was Nicholas Hotton.

Layout of the NMNH east wing as of 1963.

Hotton joined NMNH in 1959 as an Associate Curator of Paleontology. Entirely onboard with Karras’s vision and the paleobiology movement as a whole, Hotton described the old exhibits as “crowded” and “unorganized.” He thought NMNH had plenty of dinosaurs, but “mammal-like reptiles”* were sorely needed if Hall 2 was to tell the complete story of amniote evolution. Following that, Hotton’s mission over the next several years was to assemble a respectable collection of synapsid specimens for NMNH, and to incorporate them into a well-illustrated exhibit on the origins of mammals. This post highlights just a few of the specimens featured in Hotton’s version of Hall 2.

*In Hotton’s day, early mammalian relatives were usually called “mammal-like reptiles”, hence their inclusion in the fossil reptile exhibit. Today, most specialists prefer a more precise definition of reptiles that excludes synapsid (mammal-line) animals. In this post, I will be using the modern classification wherever possible.

The Dimetrodon

Prior to 1960, the non-mammalian synapsid collections at NMNH were mostly limited to early Permian pelycosaurs. The most impressive of these was a Dimetrodon gigas collected in 1917 by independent fossil hunter Charles Sternberg. One of the best collectors of his day, Sternberg worked intermittently for E.D. Cope, O.C. Marsh, and various American museums. In the summer of 1917, however, Sternberg was on a personal collecting trip with his son Levi. Their target was the Craddock Ranch bone bed of Baylor County, Texas, which was first explored in 1909 by a University of Chicago team. Sternberg was already quite familiar with this part of western Texas, having made some of the first thorough surveys of the Permian “red beds” in the 1880s, but the site itself was new to him. Nevertheless, Sternberg was extraordinarily successful that summer, collecting hundreds of fossils from a wide range of animals. He offered this bounty to the Smithsonian, and they purchased it from him immediately.

The Craddock Ranch fossils were particularly appealing because of their unique preservation. Buried in soft clay at the bottom of a shallow pond, the fossils had been removed from the ground with relative ease, and were largely free of encrusting matrix. Although few of the bones were articulated, many were identifiable. All told, the Sternberg collection included at least 35 skulls and partial skeletons from amphibians like Cardiocephalus, Diplocaulus, and Seymouria, plus hundreds of individual Dimetrodon bones, and a single articulated Dimetrodon specimen.

An early photograph of the Dimetrodon mount. Image from Gilmore 1919.

The Dimetrodon was first displayed on the north wall of the Hall of Extinct Monsters. Source

That Dimetrodon (USNM 8635) was the basis for a mount constructed by T.J. Horne. The articulated skeleton included a complete series of presacral vertebrae, the shoulder girdles, most of the forelimbs, and the left femur and tibia. The skull and jaw bones were found disarticulated, but bound together in the same mass of matrix as the skeleton. Horne added the pelvic bones and sacrum from smaller Dimetrodon specimens, and sculpted the rest of the missing material in plaster to complete the mount. Notably, his reconstructed tail was extremely short and stubby. Although the American Museum and Field Museum already had Dimetrodon mounts on display, the NMNH version stood out because of its open jaws, which Charles Gilmore said “gives the animal an appearance of angrily defying one who has suddenly blocked his path.”

Gilmore added the Dimetrodon to the Hall of Extinct Monsters in 1918. Like the other standing mounts constructed under Gilmore’s supervision, the skeleton was placed on a base textured and painted to resemble the rocks in which it was found. At this point in time, the NMNH fossil halls lacked any overarching organizational scheme, and interpretive content was minimal. Nevertheless, Gilmore displayed the Dimetrodon mount with both a small model and a 15-foot oil painting by Garnet Jex, which provided general audiences a better understanding of the animal’s life appearance.

During the 1962 renovation, Hotton re-contextualized the classic Dimetrodon mount as a mammal ancestor. Unmissable orange arrows pointed to the specific anatomical traits that signify the animal’s kinship with mammals, including heterodont teeth and a single temporal fenestra. By design, visitors would pass Dimetrodon before visiting the true mammals in the adjacent hall.

The Dimetrodon skeleton itself was altered during the next renovation in 1981, when it was placed on a new, untextured base and given a longer replica tail. Contemporary staff also repainted the plaster sections to more closely resemble the original fossils – a surprising reversal of Gilmore and Horne’s original intention to make the reconstructed bones obvious to viewers.

The Thrinaxodon

Pelycosaurs like Dimetrodon were the first major synapsid radiation, but by the middle Permian they were almost entirely replaced by therapsids. A more derived group which includes modern mammals, therapsids spread across the globe and became increasingly diverse as the Permian progressed. From weasel-sized burrowers to multi-ton herbivores, non-mammalian therapsids were among the first animal groups to conquer a wide range of terrestrial niches. Hotton wanted to tell this story in the modernized fossil exhibit, but there were hardly any non-mammalian therapsids in the NMNH collections. To correct this problem, Hotton took to the field for several months in 1960, and again in 1961. He joined James Kitching in exploring the Beafort Group rocks of South Africa, which were known to produce plentiful Permian and Triassic vertebrate fossils. Hotton returned to the museum with over 200 new specimens, the best of which were used in the renovated exhibit.

Thrinaxodon paired with Cynognathus skull. Photo by the author.

Hotton’s most prized find from South Africa was a gorgeously preserved and nearly complete Thrinaxodon liorhinus (USNM 22812). Hotton called this specimen “Baby Doll”, and while it was not prepared in time for Hall 2’s 1963 opening, it would later earn a spot of honor in the exhibit. Before that happened, though, Baby Doll was actually stolen by an over-enthusiastic volunteer. The FBI located and returned the fossil a year and a half later.

Since the 1970s, the Thrinaxodon has been displayed alongside the skull of Cynognathus crateronotus (USNM 22813), which Hotton collected on the same expedition. Both are members of the cynodont clade, which includes some of the closest relatives of modern mammals.

The Daptocephalus

Less than a month after hall 2 reopened, Nicholas Hotton returned to South Africa. This time, he was accompanied by his spouse Ruth Hotton and their three young children. For seven months, the Hottons traveled among fossil sites on different ranches, camping most nights. They collected some 300 specimens for the Smithsonian, and Hotton’s biostratigraphic mapping of the Beaufort Group brought a measure of clarity to this region’s historically convoluted geology.

Ruth Hotton made one of the trip’s most impressive finds while prospecting in a dry riverbed with her daughter, Carol (who is now a paleobotanist at NMNH). Turning a corner, she stumbled upon a dicynodont skeleton, completely exposed and lying in the middle of the channel. One can only imagine the surprise and delight of finding an articulated fossil skeleton completely uncovered. If the Hottons had been there one season earlier or one season later, the river would have undoubtedly destroyed the fossils.

Close up of the erroneously reconstructed skull. Photo by Christian Kammerer.

Back at the museum, Nicholas Hotton prepared the specimen (USNM 299746) and determined it to be Daplocephalus leoniceps, one of the plethora of dicynodonts known from the Beaufort Group. Based on this classification, he reconstructed the badly damaged skull to resemble more complete Daplocephalus specimens, and added casts of Daplocephalus limbs. As it turns out, however, USNM 299749 is not a Daplocephalus – it is a somewhat distantly related dicynodont currently called Odontocyclops (also subject to change). To varying degrees, fossil mounts are hypotheses made of bone and plaster. They are based on the best information available at the time, but sometimes they need to be corrected. The NMNH “Daplocephalus” has been mislabeled and erroneously reconstructed for many years, but the current renovation of the NMNH fossil halls now presents an opportunity to deconstruct the specimen and study it up close.

Thanks to Christian Kammerer for kindly sharing images and insight on “Daptocephalus”!

References

Gilmore, C.W. (1919). A Mounted Skeleton of Dimetrodon gigas in the United States National Museum, with Notes on the Skeletal Anatomy. Proceedings of the United States National Museum 56:2300:525-539.